Regex Tester
Write a regular expression, test it against sample text, and see matches, capture groups, and counts highlighted live.
Regex behavior may vary slightly between programming languages (JavaScript, Python, PCRE, etc.). This tool uses JavaScript's regex engine.
//g
How to Use
- 1Type a regular expression pattern.
- 2Toggle flags like global or case-insensitive as needed.
- 3Paste sample text to see matches highlighted live.
Features
- Live match highlighting
- Match count and capture group breakdown
- Named group support
- Common flag toggles (g, i, m, s, u)
- Built-in examples
Example
Click Load Example to test an email-matching pattern against sample text.
About This Tool
A regex tester lets you experiment with a regular expression against real sample text before using it in code. It highlights every match, counts them, and breaks down any capture groups so you can confirm the pattern behaves the way you expect.
This tool uses JavaScript's native regular expression engine. Other languages such as Python or PCRE-based tools implement mostly compatible but not identical syntax, so always verify a pattern in its target environment before relying on it in production.
FAQ
- Why do my matches look different in Python?
- Regex engines differ slightly between languages, particularly around named groups, lookbehind support, and Unicode handling. Always test in your target language for critical use cases.
- What does the global flag do?
- Without it, matching stops after the first match. With it enabled, every match in the text is found and highlighted.